Ground Fault Protection

What is ground fault protection and do you really need it?  A ground fault is an abnormal condition in which current is traveling along the ground wire, which is normally a non-current carrying conductor.  This means that something in the Solar Array is shorting out, causing the current to flow into the ground wire.  If the condition is left to remain, the point where the short is happening will eventually fail causing a fire.  This can be seen in two recent devastating fires caused by Solar Array Ground faults. (Bakersfield, CA and Delanco, New Jersey)

Now is where the question arises, doesn't a circuit breaker of fuse remove the ground fault?  In a ground fault, a circuit breaker of fuse may not open clearing the ground fault.  The reason behind this is that in order for a circuit breaker or fuse to trip, the current flowing through that device must be higher than the devices rating.  For example, a 20 ampere circuit breaker needs over 20 amperes to trip.  In a ground fault there may not be enough current flow to trip the breaker.

The problem with ground faults is that not all of the current is flowing into the ground wire.  There is always a certain amount of resistance that happens in a ground fault that reduces the amount of possible current.  This means that even though there is a fault, it is not high enough to trip the circuit breaker of fuse that is normally in the system.  Therefore, ground fault protection is added to the circuit.  In general, a ground fault protective device is set to trip as low as 1 ampere.

A ground fault protection device will disconnect any loads on the Solar Array.  By disconnecting the loads, there is no longer a flow of current stopping the short circuit from persisting.  Now the Solar Array is brought to a safer condition until the short can be removed from the system.

Now for the million dollar question, do you need one?  If you are planning on putting solar panels on your dwelling, the answer is yes.  A ground fault protective device will help prevent your house from catching fire due to a ground fault.  Remember, ground faults generally do not trip your normal circuit breakers or fuses.  On the other hand, if your solar panels are going to be ground mounted, this isn’t a requirement, but still a good idea.

Having a ground fault protection device installed in your Solar Array is like having insurance.

DIY Solar Panels - Fact or Fiction

In recent years there has been a surge in websites and manuals for Do-It-Yourself Solar Panels. There have been some impressive claims as well. "Say adios to your utility", "Go 100% Solar", and "Reduce Your Electricity Bill for Pennies" is probably my favorite.  As an experienced Solar professional, I can tell you all of these to-good-to-be-true claims are more fiction than fact.

In this article I will discuss what a DIY Solar module is and will help you determine when it is and isn't appropriate to use.

What is a DIY module? 

A DIY Solar module is created when solar cells are soldered together in series and parallel. The common module size you see on the market is a 36-cell configuration.  At the end of the series and paralleled cells will be two leads used to connect the module to either additional modules or a load.  At this point you will need to add glass, an encapsulant, and a frame.  This entire setup becomes your solar module. 

From this point, a basic knowledge of electricity will be required.  Some specific skills and terms you should be familiar with are: 

Soldering 

Ohm’s Law (Volts = Amps X Resistance)

Series vs parallel wiring

Bypass diodes

Basic carpentry or fabrication

Please keep in mind that this is strictly to create the Do-It-Yourself Solar module and not what you are going to do with it once completed.

You can use DIY solar modules only in limited situations.  When there is a building department, insurance company, or utility company involved your DIY Solar Panel will NOT be able to be used.  Solar Panels must be tested to UL1703 standards. Once you've constructed a solar module from an assembly of parts, this new assembly is not UL listed.  Since the above depicts the majority of DIY situations, for safety and legal reasons, we strongly suggest that you do not attach your DIY Solar Panels directly to your house. 

So what can you do with DIY Solar modules?  You can use them for portable power that do not involve the situations listed above (building department, utility and insurance company).  For example, you could connect your DIY solar module with a charge controller and battery bank.  Now you have what is considered a basic DC off-grid system.  This is great for remote water pumping.

Do not fall victim to the idea that DIY solar modules will slash your electrical rates.  When In fact, DIY solar modules are illegal to tie into your existing electrical system if you are connected to a Utility.